Method of producing iron and steel and composition therefor



United States Patent- O METHOD GF PRGDUQENG IRQN AND STEEL AND COMPGSITlfiN THEREFGR Norman F. Tisdale and Norman F, Tisdale, J12, Pittsburgh, Pa., assignors to Molybdenum Corporation of America, New York, N. Y., a corporation of Delaware N Drawing. Application July 16, 1953, Serial'No. 368,536

9 Claims. (o; ts-27 i The invention relates to 'the' productionof irons and of steelsand more especially, to the manufacture of such by procedures in which acid conditions pertain, and includes correlated im'pro'vementsarid discoveries whereby irons and steels having improved properties are obtained.

It is an object of the invention to provide a method for the production of irons and steels which employs a composition containing a rare earth oxide and'an alkaline reacting material.

Another object of the invention is theprovision of v a method in accordance with which a rare earth oxide composition may be advantageously'used in iron and "steel'lmanutacturewherein there is-presentan oxide of the group consisting of titanium, vanadium and zirconium.

'A further object of the invention is to provide a method for the'production of irons and of steels which enables rare earth oxides to be used in an acid melt with "markedly distinctive results.

A still further object of the' invention is the provision of a method for the production of irons and of steels in oxide, a reducing agent therefor and an alkaline reacting" compound is incorporatedinan'iron' containing melt.

A specific objectof the-inventionistheprovision of a composition for" utilization in the production of 'irons and steels which contains a rare earth oxide, suitably a plurality of the oxides, such as-an ore or a concentrate thereof with cerium oxide desirably being present in'preponderant amount, a reducing agent therefor, and an alkaline reacting compound. Furthermore, the composition may contain a suitable compound serving as a source of oxygen such as a nitrate, for example, sodium nitrate, potassium nitrate and the like. Moreover, it will be understood that the expression rare earth oxide'as used herein includes other suitable compounds of the rare earth metals such as carbonate, chloride and'silicide.

Other objects of the invention will in part be obvious 2,799,575 l "Patented July 16, 1957 from the presence of a member of the group consisting of oxides of titanium, vanadium and zirconium pertainis decidedly improved by the addition of an appropriate amount of a composition containing a rare earth oxide, either singly or in compatible combination, a reducing agent therefor andan alkaline reacting compound to 'a melt, that is to theliquid iron or steel. Suitably the constituents of the composition are of relatively fine size and intimately admixed, and may be in the form of a briquette. V

More especially, the procedure comprises preparing an iron containing melt, adding metallics, i. e. a material which may contain chromium, manganese, molybdenum, nickel, tungsten, columbium, cobalt, tantalum, titanium, zirconium or silicon, thereto during furnacing, deoxidizing, utilizinge. g. feri'o slicon, calcium silicon, ferro manganese and the like, and incorporating a composition which, more' particularly, contains a plurality of rare earth oxides, a reducingagent therefor and an alkaline reacting compound. The reducing agent may be a member selected from the 'group con'sisting 'of calcium, aluminum, sodium, silicon, magnesium and boron and a boride, borane, and silicide of calcium, strontium, manganese, "chromium, iron,'rnangesium, nickel, boron and'cobalt. The alkaline reacting" material may be a member of'the' group consisting of oxides, carbonates and hydroxides ofc'alcium, magnesium, barium and strontium and the carbonates and bicarbonat es of sodium and potassium. 'The' oxideconstituent and the reducing agent may be present in 'the"r'elative' proportions of about 1.0

part oxide'and' about 0.02 to about 1.0 part reducing agent suitably 1.0 part oxide and 0.3-0.7 part reducing agent, such as calcium, and 0.06-0.5, more particularly0.12, reducing agent such as calcium boride and calcium silicide. The amount of the alkaline reacting compound may be from about 0.25% to about 20.0% and suitably about 10% by weight of the composition, i. e. of the other constituents. Thus the composition may contain rare earth oxides, 50 parts; calcium silicide, 12 parts; sodium nitrate, 4 parts; lime (Ca(OH)z), 6 parts. Further, the term lime, as used herein will be understood to encompass the oxide hydroxide and carbonate of calcium. Additionally, when an oxygen source is also present in the composition it may -bein the form of a'nitra'te, a' humanist permanganatesuch asthose of sodium,p'otassiu'm, calcium and magnesium, and i-n-an amount from 'about 60% to 7 0% by weight of the reducing agent. I t

.The addition 'of 'thecomposition may beeffected a't different phases of the melting and furnacing, 'and in 'a convenient and accepted manner. A-suitable procedure is toadd itto the ladle either before, du ring or after deoxidizers 'havebeen added-"and desirably before the ladle is one-ha1ffull; that is while the ladle is less than one-half full. However, another 'andsomewhat' preferred procedure is to place it in the -bottomof the ladleand cover over with a de'oxidizersuch as calcium silicide, or it may be placed ina thick walled pipe and the ends closed, and then placed in the bottom of the ladle Where the liquid ferrous'metal-may be'poured on top of it. Either method delays the action so 'that'th'ere 'will be sufficient liquid metal to allow a proper reaction therewith. Further, we'h'tvaround that about-.1 to about spouses of the oxide composition have been added Pertoflbf'irbg meet a ve fia stain structu e esu t 9W r, p nd .ns9 2.111; pouring tempe at r h s zje of the mold, and the analysis desired, an 'amount'of about 3 pounds of the oxide composition to the ton has given beneficial results.

In the manufacture of these steels, the usual accepted good practice is employed and care is taken to see that the steel. is properly deoxidized. Further, we have found that it can be poured at a temperature which is lower than usualpractice, and. that the treatment witlrthe basic rare earth oxide-reducing agent composition increases the fluidity and notch sensitivity of the treated metal.

Various quantities of the composition have been tried and found to. be effective. However, when excessive amounts have been added, the steel has been found to' have an excess of non-metallic inclusions and as such offered low resistance to oxidation or corrosion. Our

method makes efiicient use thereof and at the'same time utilizes only a very'small amount. found that about 4.5 pounds of the oxide composition per ton may be used and satisfactory results obtained therewith, especially when added to the melt as herein described Moreover, we have and in the preferred manner.

As an illustrative embodiment of a manner in which the method may be carried out, the following examples are presented:

EXAMPLE I Casting steel A heat was made in which the steel obtained had the following approximate analysis expressed as percentages:

The power having been turned on and the charge having been melted,'the following were added during furnacing: I i

Pounds Iron ore--- 100 Nickel (plate) 38 Molybdenum tn'oxide 20 Ferro silicon (50%) 25 Ferro'chrome (6670%) 55 When the heat had been suitably worked and the slag being in proper condition, the melt was tapped and to the ladle therewere added the following:

. Pounds Ferro manganese (80-83%) 63 Basic rare earth oxide composition 6.25 Grainal 12 Aluminum 5 The basic rare earth oxide composition consisted of rare earth oxide 50 parts, .calcium boride 6 parts, sodium nitrate 4 parts, and lime 6 parts. Further, Grainal utilized herein is an alloy containing aluminum, zirconium, titanium, manganese, boron and silicon of the following approximate percentage composition:

vAluminum 13.00 Zirconium 4.00 Titanium V 20.00 Manganese 8.00 Boron V 0.5.0. Silicon 7 5.00

And the balance iron r 4 a EXAMPLE II A steel was produced according to the specification Percent Carbon 0.35-0.45 Manganese 0.80-1.10 Sulphur "maximum" 0.03 Phosphorus maximum 0.03 Nickel 0.300.5O Molybdenum maximum 0.08-0.15

and the steel obtained had the following approximate analysis expressed as percentages:

The power having been turned on and the charge having been melted, the following were added during furnacing:

Pounds Nickel (sheet) 225 Molybdenum trioxide 1'20 Ferro manganese (-83%) 1640 Ferro chrome I 500 Ferro silicon (83%) 250 Aluminum Grainal 480 When the heat-had been suitably worked and the slag being in proper condition, the melt was tapped and to the ladle there were added the following:

' Pounds Calcium silicide 340 Aluminum 35 Basic rare earth oxide composition 240 The basic rare earth oxide composition utilized contains rare earth oxide 50 parts, calcium silicide 12 parts, sodium nitrate 4 parts, lime 6 parts and Grainal was of the same composition as in Example I.

Themethod herein described for the. production of iron and steel leads to the formation of a fine grain structure which'enhances the resistance to corrosion. This, of course, attends usually only when the procedure is followed as set forth hereinabove in this application. The amounts to be used, as suggested above, depend upon the composition of the steel, but we have found that not more than about 4.5 pounds per ton of rare earth oxide composition need be employed and chemical analysis of the finished steel shows a rare earth metal content not greater than 0.018%, expressed as cerium. When steel has been treatedwith the basic rare earth oxide-reducing agent composition, and a fine grain thus produced, the steelpossesses decidedly better resistance to corrosion and oxidation and, in addition, higher impact values at room and'at low temperatures. .These properties can be used to advantage; the first inv stainless steel of various types and the second in such applications as to shockimust beofthe highestorder.

The results show that there are several advantages which accrue to the user of the composition when employed in the manner described herein. Thus, one may use a standard material and obtain'decided benefits due to its resistance to corrosion and oxidation. Further, the analysis may be varied, so that less of a scarce and costly alloy will be employed to obtain the same results as the same untreated material with a larger amount of the .alloy.

In the melting and casting, certain precautions have been found to be beneficial and are recognized as being proper practice. For instance, a good pouring temperature for a steel would be 2740 F. We have also found that the melt, aftertreatment in the ladle, should be poured immediately to insure quick freezing of the metal, and in some instances a thick walled ingot mold serves to effect the quick freezing. Due to the fact that slags cause reaction at the point of contact with the metal, it has been found that chilling the slag reduces such action, and this may be accomplished by the addition of slag making material suchas dolomite, burnt lime, and the like. Among the advantages attending the use of the alkaline reacting compound oxide-reducing agent composition are a reduction of the sulphur content and the obtention of a fine grain as cast. These occasion higher impact values at room and at low temperatures, and such values are especially important in those types of steel which must function properly and safely at low temperatures, e. g. those in the arctic and antarctic regions.

Furthermore, when molten ferrous material has been treated as herein described, a fine grain results and later certain definite improved physical and chemical characteristics are obtained. Also, it is highly desirable to make the iron or steel so that this fine grain, as cast, persists. This is accomplished by casting at a relatively low temperature, and tapping or teeming as quickly as possible to solidify the material.

We have observed that if, after treatment with the substance which endows it with these fine grain properties, the metal is allowed to remain in a liquid state for a long period of time, the fine grain gradually disappears and the resultant steel compares in almost every way, with an untreated steel. Moreover, when a melt is so treated and subsequently cast as a sand casting, whose solidification rate is very slow, a very small reduction in the grain size is obtained, which indicates that retention for a long time after treatment in a liquid state allows the force which produces the fine grain to be dissipated and, hence, the fine grain qualities are not attained.

A distinctive characteristic of this treatment is that only a small amount of the oxide composition is used, and this is such that analysis of the finished steel shows that the quantity added is no longer existent and the rare earth metal content desirably may range from about 0.003% to 0.009%, and suitably will be about 0.005%. This indicates that it is not the presence of an alloy which confers this fine grain property but rather an effect which is considered to induce nucleation.

It may be added, that irons and steels, and particularly certain stainless varieties, having a tendency to solidify in large dendrites have a much smaller grain size as-cast than the untreated metal. This finer grain size improves the rolling qualities, increases resistance to corrosion, and gives a relatively high impact value at low temperatures.

Since certain changes in carrying out the above method, and certain modifications in the composition which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of. the invention herein described, and all statementsoftheascope of the-invention which, as a matter of;language, might be said to fall therebetween.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

1. A. composition of matter containing a rare earth oxide in intimate admixture with a reducing agent therefor, and analkaline reacting material in finely divided condition, said composition being for the production of iron and steel and the oxide constituent and the reducing agent being present .in the proportions of about 1.0 part oxide and about 0.02 to about 1.0 part reducing agent and the alkaline reacting material in an amount about 10% of the other constituents.

2. A method for the production of iron and steel which comprises preparing an iron containing meltin which .an acid condition pertains arising from the presence'of a member of the group consisting of oxides of titanium, vanadium and zirconium, adding a metal containing material thereto during furnacing, deoxidizing, and incorporating a composition as defined in claim 1 containing a rare earth oxide, a reducing agent therefor, an alkaline reacting material, pouring and quick freezing.

3. A method for the production of iron and steel which comprises preparing an iron containing melt in which an acid condition pertains arising from the presenec of a member of the group consisting of oxides of titanium, vanadium and zirconium, adding a metal containing material thereto during furnacing, deoxidizing, incorporat ing a composition as defined in claim 1 containing a rare earth oxide, a reducing agent therefor, and lime, pouring and quick freezing.

4. A method for the production of iron and steel which comprises preparing an iron containing melt in which an acid condition pertains arising from the presence of a member of the group consisting of oxides of titanium, vanadium and zirconium, adding a metal containing material thereto during furnacing, deoxidizing, incorporating a composition as defined in claim 1 containing a plurality of rare earth oxides, cerium oxide being present in a preponderant amount, a reducing agent therefor, and lime, pouring and quick freezing.

5. A method for the production of iron and steel which comprises preparing an iron containing melt in which an acid condition pertains arising from the presence of a member of the group consisting of oxides of titanium, vanadium and zirconium, adding a metal containing material thereto during furnacing, deoxidizing, adding a composition as defined in claim 1 containing a rare earth oxide, a reducing agent therefor, and an alkaline reacting material to the ladle during tapping, and while the ladle is less than one-half full, and quick freezing.

6. A method for the production of iron and steel which comprises preparing an iron containing melt in which an acid condition pertains arising from the presence of a member of the group consisting of oxides of titanium, vanadium and zirconium, adding a metal containing material thereto during furnacing, deoxidizing, incorporating a composition as defined in claim 1 containing a rare earth oxide, a reducing agent therefor, selected from the group consisting of calcium, aluminum, sodium, silicon, magnesium and boron and a boride, borane and silicide of calcium, strontium, manganese, chromium, iron, magnesium, nickel, boron and cobalt, and an alkaline reacting material, pouring and quick freezing.

7. A composition of matter containing a rare earth oxide in intimate admixture with a reducing agent therefor, and lime in finely divided condition, said composition being for the production of iron and steel and the oxide constituent and the reducing agent being present in the proportions of about 1.0 part oxide and about 0.02 to about 1.0 part reducing agent and the alkaline reacting material in an amount about 10% of the other constituents.

for, an alkaline reacting material in finely divided condi- 7 tion and a compound serving as an oxygen source, the oxide constituent and the reducing agent being present in the proportions of about 1.0 part oxide and about 0.02

to about 1.0 part reducing agent, the alkaline reacting material in an amount about 10% thereof and the oxygen source compound in an amount from about 60% to about 70% by weight of the reducing agent, said composition being for the production of iron and steel.

9. A composition of matter for the production of iron and steel having the following approximate composition:

Parts Rare earth oxide 50 Calcium boride 6 Sodium nitrate 4 Lime 6 said composition being in intimate admixture and the lime in finely divided condition.

References Cited in the file of this patent UNITED STATES PATENTS 1,623,757 Saklatwalla Apr. 5, 1927 2,194,965 Andrieux Mar. 26, 1940 2,203,214 Doom' June 4, 1940 2,280,872 Udy Apr. 28, 1942 2,370,610 Adeline Feb. 27, 1945 2,683,662 Tisdale et al July 13, 1954 FOREIGN PATENTS I 20,884 Great Britain 1905 11,606 Great Britain 1907 

1. A COMPOSITION OF MATTER CONTAINING A RARE EARTH OXIDE IN INTIMATE ADMIXTURE WITH A REDUCING AGENT THEREFOR, AND AN ALKALINE REACTING MATERIAL IN FINLY DIVIDED CONDITION, SAID COMPOSITION BEING FOR THE PRODUCTION OF IRON AND STELL AND THE OXIDE CONSTITUENT AND THE REDUCING AGENT BEING PRESENT IN THE PROPORTIONS OF ABOUT 1.0.PART OXIDE AND ABOUT 0.02 TO ABOUT 1.0 PART REDUCING AGENT AND THE ALKALINE REACTING MATERIAL IN AN AMOUNT ABOUT 10% OF THE OTHER CONSTITUENTS. 